Discussion

Dr David Calcagno (Camp Hill, PA). I had a question about your method of embolization. Were these coils placed into the distal hypogastric and its branches, or were you occluding these at the origin of the internal, such as is done with the Amplatzer Plug? We found that when we placed an Amplatzer Plug in the proximal internal iliac, thus preserving the distal collateral communication, that the occurrence of buttock claudication was less than when we placed conventional coils in the branches of the internal iliac.

Dr W. Anthony Lee. I am glad you asked that question, because that debate has been going on for some time. Whenever possible, we try to do a truncal embolization. We have not used the Amplatzer plug until very recently in our practice. And on occasion when the coils were undersized they did migrate into one of the branches. We actually looked at the subset of patients who had so-called branch embolizations, either inadvertently or purposefully, vs those who had only truncal embolizations. There was no difference in terms of their incidence of buttock or thigh claudication. So although others have proposed this as a potentially better technique, we have not been able to duplicate those same results in our series.

Dr Frank Veith (Riverdale, NY). I agree with your conclusion that, when possible, one should revascularize the hypogastric artery. However, there are times that it is very difficult or impossible to do so, for example, with hypogastric aneurysms. Together with Mannish Mehta from Albany, we have had over 160 patients in whom we have performed unilateral hypogastric coiling or occlusion, and more than 60 patients who have had bilateral hypogastric coiling or occlusion. Our incidence of buttock claudication at one year in both those groups of patients ranges between 14% and 16% in those patients. It is not terribly disabling, except in the very rare patient. In addition, there have been no serious complications such as colon necrosis, buttock necrosis, neurological deficits or other severe complications.

So I believe that when there is no other easy option, it is safe to occlude one and even both hypogastric arteries. I, and several others, believe that the problems that have been reported with hypogastric interruption have been due to microembolization, because coiling of the hypogastrics can require manipulation in clot filled, dilated common iliacs, which can cause embolization to the small branches of the hypogastric arteries. Our bottom line, however, is that hypogastric interruption, when necessary, is a relatively safe and justifiable procedure. The question I would ask Dr Lee is how often were you unable to revascularize the hypogastric arteries because of technical factors?

Dr Lee. Although we didn’t specifically look at that, in my recollection I would say very few. One or two at most from technical problems. But overall, Dr Veith, I would agree with your conclusions. If you have to do it to complete the repair, I think you should. And your numbers of 14% to 16% at 1 year would be consistent with a prior study that I was involved in where we did look at some late outcomes of the initial buttock claudication, and about 50% of them did resolve to a certain extent by 1 year.

Dr Roy Greenberg (Cleveland, Ohio). I have a comment and question relating to the incidence of limb occlusion in the absence of antegrade hypogastric flow and what you believe the potential etiologies for the limb thrombosis are.

In our series, of the 21 branch cases that we published, there were three limb occlusions, and they were always in the setting of the contralateral limb or nonbranched limb or, in one case, following a failed branch where an internal iliac dissection precluded branch patency. Thus, all limb occlusions occurred in the absence of antegrade internal iliac artery flow. In your series, you had the similar numbers and you found statistical significance. But why do you think these limbs really occlude? Is it because the external iliac artery is smaller than the common iliac artery? But if that were the case, why wouldn’t the branched limbs or bypassed limbs occur at the same rate? Were the grafts used for excluded internal iliac arteries too oversized, or was there a stiffness mismatch between the graft and arteries? Alternatively, did this possibly relate to increased tortuosity in these patients?

Dr Lee. I think it is definitely multifactorial. As I mentioned before, I believe that there is a role of the hypogastric artery as an important outflow vessel. When we looked at those patients that had limb occlusions, there was a combination of factors including external iliac occlusive disease, small size, and some mechanical factors resulting in mild kinking. Patency of these endograft limbs is excellent. And even in very large series, you only have very few numbers to work with. So it is difficult to tease out which of these factors are the most important.

Dr William Turnipseed (Madison, Wis). I find this debate very interesting. Once we embrace the concept of endovascular repairs, the early conversations seem to accept as a given that we would tolerate the complications of interfering with the hypogastric artery. Obviously, that philosophy has changed over time, and this paper is a good reflection of that whole paradigm change in the management of endografts.

We have taken a somewhat different approach, and a couple of years ago, actually, published a paper in which we covered the hypogastric with the endograft, particularly in unilateral aneurysm repairs. The point of this was that our complication rate was absolutely minimal. We had a similar number of patients, 35 patients, two of which developed transient claudication, and these episodes of claudication resolved within 2 months. We had no other complications and no type II endoleaks. All of these vessels on follow-up angiography had occluded the main trunk and preserved the pelvic collaterals.

My question would be, have you looked at the prospect of simple coverage for unilateral aneurysm repairs and avoided many of these other addendum procedures that carry with them a cost and risk?

Dr Lee. We have not looked at that per se. But, obviously, we have had cases of inadvertent hypogastric artery coverage, so that would fall into that general technique. And other techniques have been described, such as the sleeve technique of flush occlusion. But because of the concern for a type II endoleak and no subsequent access to that vessel if that were to occur, we have elected not to take that chance and preemptively either revascularize or embolize the hypogastric artery.

Dr Robert Zwolak (Lebanon, NH). I have a question about the incidence of buttock claudication despite the placement of your hypogastric grafts. If I noted the data accurately, your patients experienced a 37% incidence of buttock claudication in the embolization group and a 27% incident in the bypass group. How do you dissect that out? Why are so many of the bypass patients still claudicating?

Dr Lee. In almost every one of the 27% in the hypogastric bypass group, with the exception of one patient, it occurred in patients who had bilateral iliac aneurysms where the contralateral hypogastric artery was embolized, and they were claudicating on that contralateral side. The one patient who developed claudication on the side of the bypass was the one of early graft thrombosis of the hypogastric bypass from a technical complication.

Dr Michel Makaroun (Pittsburgh, PA). So do you presently do bilateral bypasses if you have bilateral aneurysms?

Dr Lee. The hypogastric bypass adds a good hour and a half to the overall length of the procedure, depending on the body habitus and whether there has been any kind of pelvic surgery in the past. So doing bilateral bypasses, unless the patient is a prohibitive surgical candidate, you might as well just perform a regular open repair.